Several days ago, I changed my email address and password for my Apple I.D. No problems with my iPad or iPhone. In fact I've ordered music and a movie on both with no problems. However, I keep getting an annoying pop-up on my iMac telling me there's a problem with my email address. It lists my old email in the message. It says to open "iCloud Preferences" to fix the problem. I click the little iCloud preferences button and nothing happens. It just sit there, spinning it's little wheel icon forever. I waited about 30 minutes for it to open to no avail. Any help would be appreciated. Thanks in advance.